The role of Spodoptera exigua multiple nucleopolyhedrovirus genes se76 and se 28 on viral pathogenicity

Abstract

Six Spanish genotypes of the Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) differ in their efficiency for vertical and horizontal transmission as well as in their pathogenicity (mean lethal dose), virulence (speed of kill) and productivity (number of progeny virus per insect). Whole genome sequencing of these genotypes could pinpoint genes involved in host pathogen interactions. The slowestand fastest killing viruses had a mutation in the SeMNPV ORFs se76 (cg30) and se28, respectively. The cg30 encoded protein, featuring two nucleic acid binding sites, a zinc finger, and a leucine zipper, is considered a prime candidate for the regulation of baculovirus late expression products. The function of se28 is not known, although it has been determined as non essential because of the existence of natural viral genotypes lacking this gene that can replicate both in vitro and in vivo. In this study we examined the influence of these genes in the pathogenicity of SeMNPV with two knockout recombinants, SeBAcAL1null76 and SeBacAL1null28, which were constructed using the bacmid based recombination system.